Tag: cell-the basic unit of life

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Questions Related to cell-the basic unit of life

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

What are the three major functional regions of a cell?

  1. (i) Plasma membrane, (ii) Cytoplasm and (iii) Nucleus

  2. (i) Plasma membrane, (ii) Lysosome and (iii) Ribosome

  3. (i) Cell wall, (ii) Lysosome and (iii) Ribosome

  4. (i) Cell wall, (ii) Cytoplasm and (iii) Nucleus
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There are three major functional parts of the cell such as plasma membrane, cytoplasm and nucleus. Plasma membrane regulates the particles entering or leaving the cell. It carries out endocytosis, exocytosis and transport of various substances through different carrier proteins. It is also involved in cell signaling. 
Cytoplasm is a gel-like substance present in all cells. All of the cell organelles are suspended in the cytoplasm. Most of the cellular activities as metabolic pathways like glycolysis, key processes like cell division occur in the cytoplasm. Nucleus regulates all the cellular activities by controlling the enzymes required for cellular processes. The four main cellular functions of the cell are protein synthesis, cell division, growth and differentiation are carried out by the nucleus. 

So, the correct answer is option A.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

A nucleus is absent in the mature

  1. Sieve tube cells.

  2. Mammalian erythrocytes.

  3. Monocytes.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sieve tubes are cells of phloem found in certain plants and help in long distance translocation and distribution. Their nucleus is fragmented and disappeared. Mammalian erythrocytes also called as red blood cells are formed in bone marrow from multipotential hemocytoblast and further converted to erythroblast (normoblast). The nucleus and mitochondria of erythroblast disappear and it is converted to mature erythrocyte with haemoglobin. Erythrocytes cannot multiply as they lack the nucleus and can survive for 100-120 days. Monocytes are immune cells of the human body and are capable of dividing into macrophages. So they have the well-defined nucleus. So nucleus is absent in sieve tube cells and mammalian erythrocytes.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

A eukaryotic organelle that can best be seen with the light microscope is the:

  1. Endoplasmic reticulum

  2. Nucleus

  3. Polyribosome

  4. Microtubule
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The nucleus is membrane-bound organelles which are seen under a light microscope because of its large size. These are spherical in shape and encompasses nuclear membrane, chromosomes, nucleoplasm and nucleolus. It contains the cell's genetic material.

Hence, the correct answer is 'Nucleus'.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

How many membranes comprise the nuclear envelope?

  1. One

  2. Two

  3. Three

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The nuclear envelope is a membrane barrier that separates the nucleus from the cytoplasmic in eukaryotic cells. It contains a large number of proteins. The nuclear envelope is composed of two concentric bilayer membranes. The two layers are fused together into numerous tiny holes called the nuclear pores.

Hence, the correct answer is 'Two'.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

The nucleus is not important as the site of:

  1. DNA synthesis

  2. RNA synthesis

  3. Synthesis of ribosomal subunits

  4. Protein synthesis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The nucleus is a spherical organelle which is present in eukaryotic cells. The main function of the nucleus is to control gene expressions. It synthesizes RNA and DNA. Protein synthesis takes place in Ribosomes in the cytoplasm

Hence, the correct answer is 'Protein synthesis'.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Which of these is not found in the nucleus?

  1. Nucleoplasm instead of cytoplasm

  2. Functioning ribosomes

  3. Chromatin that condenses to chromosomes

  4. Nucleolus that produces rRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ribosomes are synthesized in the nucleolus but function in the cytoplasm. Therefore, functioning ribosomes are not found within the nucleus.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Acetabularia used in Hammerling's nucleocytoplasmic experiments is

  1. Unicellular fungus

  2. Multicellular fungus

  3. Unicellular uninucleate green alga

  4. Unicellular multinucleate green alga
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Acetabularia is a genus unicellular or single-celled green algae belonging to the family Polyphysaceae which are found in subtropical waters.

  • They are gigantic in size and complex in form, therefore, used in experiments in cell biology.
  • Hammerling's nucleocytoplasmic experiments state that the cytoplasm is the centre for all the metabolic activities in the cell and the nucleus is the controlling centre. 
  • So, the correct answer is 'Unicellular uninucleate green alga'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Hammerling's experiments on Acetobularia involved exchanging

  1. Cytoplasm

  2. Nucleus

  3. Rhizoid and stalk

  4. Gametes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Acetabularia cell is composed of three segments: the "rhizoid" or base which contains the nucleus, the "stalk," and the "cap." 
  • In his experiments, Hammerling grafted the stalk of one species of Acetabularia onto the rhizoid of another species. In all cases, the cap that eventually developed on the grafted cell matched the species of the rhizoid rather than that of the stalk.
  • This experiment shows that the base is responsible for the type of cap that grows. The nucleus that contains genetic information is in the base, so the nucleus directs cellular development.
  • So, the correct option is 'Rhizoid and stalk'.
Multiple choice bio-chemistry cell-the basic unit of life introduction to cell discovery and cell theory cell discovery cell discovery and cell theory cell as structural and functional unit

Match column I with column II and select the correct option from the codes given below.

Column - I Column - II
A. Leeuwenhoek (i) First saw and described a living cell
B. Robert Brown (ii) Presence of cell wall is unique to plant cells
C. Schleiden (iii) Discovered the nucleus
D. Schwann (iv) All plants are composed of different kinds of cell
  1. $A - (i), B - (iii), C - (iv), D - (ii)$
  2. $A - (i), B - (iii), C - (ii), D - (iv)$
  3. $A - (iii), B - (i), C - (iv), D - (ii)$
  4. $A - (i), B - (iv), C - (ii), D - (iii)$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The first man to witness a live cell under a microscope was Anton Von Leeuwenhoek.
  • Robert Brown was responsible for discovering the nucleus of a cell.
  • Matthias Jakob Schleiden started that all parts of the plant organism are composed of different kinds of cell.
  • Theodor Schwann studied that cells had a thin outer layer which is today known as plasma membrane. He also concluded that the plant shows the presence of a cell wall is a unique character of plant cells.
  • So, the correct option is " A-(i), B-(iii), C-(iv), D-(ii).